1. Field of the Invention
The invention relates to systems for qualification of chemical decontamination procedures for nuclear reactor coolant systems, and, in particular, to an arrangement for test decontamination of reactor coolant pump seals for use in a test decontamination loop.
2. Background of the Invention
Nuclear reactor systems, such as those used for electric power generation, are typically cooled by water flowing through channels in the reactor core. Pressurized water reactor (PWR) systems include a closed loop primary coolant system circulating coolant water between the reactor core and the heat exchangers used for steam generation. During operation of the nuclear power plant, surfaces of components in the core and in the primary coolant system can corrode. The corrosion products, generally referred to in the industry as crud, can be activated by transport of the corrosion products to the core region by the reactor coolant system (RCS). The activated crud can be subsequently released from the core region and redeposited elsewhere in the system, thereby producing radiation fields throughout the piping and components of the primary system. The activated crud distributed in the primary system creates a radiation hazard for workers during routine maintenance and refueling outages.
It is therefore desirable to be able to periodically decontaminate the primary system using chemical treatment of the primary coolant water to remove crud from the primary system without having to dismantle its component parts. Any such chemical decontamination procedure first must be qualified and tested to assure that the procedure does not cause significant degradation of core and primary system components that may adversely impact the function, design capability, or life of the RCS.
U.S. Pat. No. 5,126,100, entitled "System for Qualification of Chemical Decontamination Methods for Decontamination of Nuclear Reactor Systems", incorporated herein by reference, discloses a method and apparatus for assessing the feasibility of employing particular chemical decontamination processes to remove crud from primary systems in nuclear reactors without adversely affecting the integrity of the components and piping during further reactor operation. A simulator apparatus allows coupons of material within a test housing to be subjected to a variety of temperatures and pressures in order to simulate a decontamination process within an actual RCS. The exposed materials can then be evaluated to assess the impact and acceptability of the decontamination processes and/or the materials used.
However, U.S. Pat. No. 5,126,100 does not disclose an apparatus or method for controlling flow characteristics over surfaces of primary system components, such as RCP seals, to reproduce flow fields that would be experienced by the components used in an RCS. Total flow through the test housing can be varied, but not the direction and magnitude of the flow across any particular surface.
In order to more accurately assess the feasibility of any decontamination procedure in the test loop, it is desirable to arrange the component parts being test decontaminated in a manner that accurately reproduces typical operating conditions in a primary system, and in particular, flow characteristics. Therefore, there is a need for an apparatus for arranging primary system component parts, such as reactor coolant pump (RCP) seals, that will permit selection of direction and magnitude of process fluid flow across selected surfaces of the component parts within a test housing. This will, in turn, permit close simulation of the flow characteristics in an operating primary system during an actual chemical decontamination procedure.